pimpimusmaximus

I have been running an inline fuel pump (255 LPH Walbro), but keep having vapor lock issues. I have decided to go with an in-tank pump. My 84 did not have an in-tank pump. Is it possible to just swap the sending units and get a aeromotive stealth in-tank pump? I refuse to cut my car and so I will be dropping the tank to do it. Do I just swap sending units or buy a TPI tank with appropriate sending unit and just swap the pump?

five7kid

iTrader: (14)

Getting an EFI tank (TPI, TBI, V6, doesn't matter) would be the "better" way because of the baffles inside. But, I just put an EFI pickup in my carb tank, haven't really had issues.

pimpimusmaximus

Is the wiring different for in-tank pump sending units? I know that the pump has to be wired, I'm referring to the fuel level sender etc.

five7kid

iTrader: (14)

Yes. The carb'd w/o in-tank electric pump harness goes to the rear corner of the car. The EFI harness goes to the wall behind the rear seat back. The number of wires and connectors are also different (as you might expect).

But, if you send the fuel level signal through the same circuit as the old carb'd sender did, the gauge will work fine.

camarotucker

iTrader: (2)

To fix vapor lock all you have to do is put clothes pins (wood) on the fuel line.

pimpimusmaximus

I have the hot cam and a 355 bore as well as shorty headers. Do I need to upgrade the fuel pump or will an OE replacement Bosch work?

cowansauto

iTrader: (2)

Ive been wondering why people don't just use the factory setup on the LS or LT1 conversions. AC DELCO EP241 was what I used on a K5 Blazer conversion and it worked fine. That way you can use a FI sending unit, GM fuel pump, etc.

pimpimusmaximus

UPDATE

I think I have finally fixed the problem. I replaced my Walbro 255 lph inline pump with an intank pump. I changed the tank to a fuel injected tank (for the baffles), but I don't think a car that was origionally carb'd would have to swap tanks. I put a new Bosch in-tank pump in and wired everything back up. No stalling. I think the issues was 2 fold. 1st was the inline setup. I was having cavitation and vapor lock. The gas does get heated in the return style system in the LT1. Having an inline pump places the fuel under vacuum. When under vacuum, it lowers the boiling point of the gas causing fuel to boil in the line prior to the fuel pump (cavitation). Since the fuel also lubricates the fuel pump, the bubbles from boiling would allow the pump tp heat up and make the effect worse. Once this process started, it would become a downward spiral.

The 2nd part was the fuel pressure regulator. I replaced the on rail regulator with a spare I had and now it runs much better. I am still having hard starts, but I think that is because the "newer" FPR is better than the other, but not 100%. I also noted that after a 30-45 min drive, it would bog down at WOT and not spin the tires. While this still needs addressed, it is not needed for daily driving. I have been driving it now for 3 days to and from work (22 miles each way) plenty of time to heat up and have been in bumper-to-bumper traffic for upwards of 30 mins, still with no problems. I ordered an on-rail FPR from Aeromotive and that should completely fix the entire situation.